Vitamin D is one of the indispensable nutrients for the development of normal physiological functions of the bones. Proper supplementation of vitamin D can produce direct benefits to the bones, such as improving the body’s muscle strength, regulating balance, indirectly promoting the health of the bones, and also promoting the absorption of calcium in the gastrointestinal tract. There are two main ways to obtain vitamin D. The first is through sunlight exposure, which requires direct exposure of the skin to sunlight, and the acquisition of vitamin D is proportional to the exposed area of the skin; the second is through food, such as eating cod liver oil, nuts, egg yolk and other foods.